The present invention relates to a new and distinct hybrid of Coreopsis and given the cultivar name ‘Ruby Frost’. Coreopsis is in the family Asteraceae. This new cultivar originated from a controlled cross of Coreopsis ‘Rum Punch’ (U.S. Plant Pat. No. 18,889), as the seed parent and Coreopsis lanceolata ‘Sonnenkind’, an unpatented plant, as the pollen parent. Compared to the seed parent, Coreopsis ‘Rum Punch’, the new hybrid has white-edged, red purple flowers rather than orange-rose flowers. Compared to the pollen parent, Coreopsis lanceolata ‘Sonnenkind’, the new hybrid has white-edged, red purple flowers rather than yellow orange. The closest known variety known to the breeder is ‘Cranberry Ice’ (U.S. Plant Pat. No. 19,470), the new hybrid is much more compact than ‘Cranberry Ice’. The new hybrid has a clear white edged petal rather than the mottled white edged petal of ‘Cranberry Ice’.